Hydrocarbon conversion with friedel-crafts type catalyst



R. c. wAuGH Aug. 5, 1947.

HYDROCARBON CONVERSION WITH FRIEDEL-CRAFTS TYPE CATALYST Filed Aug. 1s.,1945 2 Sheets-snee; 1

@Wiley Aug 5y 947 v R. c. WAUGH -2,425,074

HYDROCARBON CONVERSION WITH FRIEDEL-CRAFTS TYPE CATALYST Filed Aug. 16,1945 2 Sheets-Sheet 2 N I v .7% olf/eey.'

Patented Aug. 5, 1947 HYDROCARBON CONVERSION WITH FRIEDEL-CRAFTS TYPECATALYST Richard C. Waugh, Hammond, Ind., assigner to Standard OilCompany, Chicago, Ill., a corporation of Indiana Application August 16,1943, Serial No. 498,808

This invention relates to reactions with Friedel- Crafts type catalystsand it pertains more particularly to improved methods and means forintroducing catalyst into continuous light normally liquid parafflnichydrocarbon reaction systems and improved method and means forpreventing catalyst carry-over from such systems.

The invention is generally applicable to conversion processes employingboth Friedel-Crafts type catalysts and paraiiinic hydrocarbons of thelight gasoline boiling range and it is particularly useful in processesfor the isomerization, disprcportionation or alkylation of said lightparaffinic hydrocarbons. In continuous isomerization systems forexample, a vexatious problem has been that of introducing make-upcatalyst to the system in amounts sufficient to maintain optimumcatalyst activity but insuiiicient to cause catalyst losses with theproduct stream. An object of my invention is to provide a solution tothis problem.

A further object is to simplify the step of adding make-up catalyst andthe equipment required therefor. A further object is to increase theelica ciency and effectiveness of such isomerization systems. A furtherobject is to obtain greater product yields per pass and greater productyields per unit of catalyst employed than has heretofore been possible.Other objects will be apparent as the detailed description of thisinvention proceeds.

It is known that aluminum chloride is approciably soluble inhydrocarbons such as pentane and hexane and that the solubilityincreases rapidly with rise in temperature. I have disu covered,however, that it is possible to maintain in hydrocarbon solution at agiven temperature, an amount of aluminum chloride substantially inexcess of that indicated by the solubility of said aluminum chloride atsaid temperature. For example, if pentanes or other paraiiinic lightnaphtha hydrocarbons are saturated with aluminum chloride at 250 F. andthen cooled to 212 F., said hydrocarbons will contain about :S1/2% byweight of dissolved aluminum chloride as comn pared to only 11/2 byWeight which is the maximum which can be dissolved when the 212 F.temperature is approached from the low side. This phenomenon does notappear to be one of simple supersaturation because the increased amountof dissolved aluminum chloride stays in solution even when permitted tostand in contact with an undissolved aluminum chloride for a long periodof time. I am unable t'o account for this phenomenal increase in theamount of aluminum chloride which can thus be held in light parafnichydrocarbon solution but'a pos- Claims. (Cl. 260-683.5)

Cil

sible explanation is that aluminum chloride molecules are in some stateof association with each other at lower temperatures, that the moleculestend to become more dissociated at higher ternperatures and when thedissociated molecules are actually dissolved in the paraiiinic solventthey tend to remain dissolved even when the solution is cooled to lowertemperatures at which the normal association would prevent solution.

In isomerization and other hydrocarbon conversionprocesses employingFriedel-Crafts type catalysts there is a pronounced tendency towardaluminum chloride complex formation and this complex itself may serve asthe active catalyst for eiecting the conversion provided that it ismaintained at proper activity. I have discovered that up to a rathercritical point aluminum chloride is preferentially soluble in thecomplex. The heat of hydrolysis of the complex may be employed todetermine the point at which the remarkable solubility of aluminumchloride in the complex is no longer effective for selectively removingsubstantially all dissolved aluminum chloride from the light paraiiinichydrocarbon solution. Thus, at 212 F., where the normal aluminumchloride solubility in pentane is about 11/2 by weight and where as muchas 3/2 aluminum chloride may be dissolved in pentane in accordance withmy invention, I have found that at 212 F., a complex which has a heat ofhydrolysis below about 380 to 400 calories per gram will selectivelytake up aluminum chloride from the solution so that the total amount ofaluminum chloride remailling in the hydrocarbon will not substantiallyexceed about .01% by weight. At higher heats of hydrolysis it will befound that substantial amounts of aluminum chloride will remain in thehydrocarbon solution in spite of thorough contact with a large amount ofcomplex.

Instead of employing heat of hydrolysis as a criterion I may employ thepercent of bound hydrocarbon in the complex. When the complex containsat least 23% by Weight of bound hydrocarbon it selectively removessubstantially all dissolved aluminum chloride from a light hydrocarbonsolution at 212 F. but when the complex contains materially less than23% of bound hydrocarbon in its composition, appreciable amounts i ofaluminum chloride will remain in the paraffin hydrocarbon solution. Thusa saturated pentane solution of aluminumchloride which has beencontacted with a complex ycontaining only about 20% or less of boundhydrocarbon may give an eflluentstream which contains a hundred times asmuch dissolved aluminum chloride as the effluent stream obtained bycontacting at the same temperature with a complex containing or more ofbound hydrocarbon.

My invention is based on these newly discovered phenomena and on thefurther phenomena regarding complex formation itselibyr reaction of?aluminum chloride with hydrocarbon. Whilecom plex formation is desirablein the conversion zone itself it is undesirable in solution tankswherein *.1 make-up aluminum chloride is .being .dissolved..in.,

incoming charging stock. Obviously-the; solution rate is markedlyIdiminished if" the surfaces of' solid aluminum chloride become;coated-i with.`

gummy iilms of complex. Complex formationi tends to increase withincreases in temperature. I have found, however, that complex formationin the solution tanks may be substantially avoided with a hexane orheavier feed by operatingsaidl tanks under substantialhydrogenpressures, particularly when care istaken toprevent the. intro-. ductionof hydrogen chloride. into said solution tanks and when that portion ofthe charging stocks which is passedthrough the solutiontanksispreviously treatedto removeobjectionable complex-forming material.While. the absence4 oi. hydrogen chloride is particularlyV important,when charging stocks heavier than pentanes, evenhy` drogen chloride maybetolerated` in the absence, ofk materials heavier, than pentanes if. a.substantial hydrogenpressure. ismaintainedin the. solu-` tion tanks.

In practicing my invention Imaintainthe. activity of an aluminumhalide.-hydrocarbon.come` plex catalysty by introducing niakefup.aluminum halide suchas aluminumlchlc-ride., aluminum bromide or, otheractivemetalhalide dissolvedjin a portion ofv the paranic light.hydrocarbons which are introduced into the reaction zone. In order tocbt-ain the necessary amountof' catalyst ins-elution Imay eiect solutionformationat a higher temperature thanthe solution utilizationtemperature and under a'. pressurel sufficient to maintain. liquidphase. conditions. Ii may then cool the resulting solution therebyobtainingthe incorporation of about twiceas much catalystin thehydrocarbons aswould otherwise-be possible. This higher terriperatureAsolution step followed by cooling isparticularly important in thosecases wherein a partof the chargingjstock'must be employed for absorbinghydrogen chloride from recycled gases so thatonly a relatively smallamount of the total hydrocarbons are available for'the preparation ofcatalyst solutions,

In order to prevent complex formationv the solution tank I may operatesaid tank undera hy'- drogen pressure and' I'may employin said' solutiontank a portion ofthe charge which has pre'-y viously been treatedfor-the removal of objece tionable complex-formingmaterials; Foroperation at 212 F. the rate orcatalystaddition tothe reactor isregulated tomaintain a heat of-hydroiysis below aboutA 380 calories'Vper lgrain and leer.; -tainly below about 400 caloriesfpersgramgof'comeplex.; In other; words; Ijinsure thatthecomplex -willLcontain at leastabout;23% `ofzboundthydrocarbon in its composition. Bythis means-I mayoperate an. iso-merization or` other: conversion precesscontinuouslyfor. longfperiod's'offtime.` with maximum conversions per passandmaximum yields per unitof-catalyst. 'Iheintroduced active metal vhalideis. selectively taken Vupwby the come plex in the conversion zone sothat the effluent product stream from the conversion zone con: tains a.negligible amounto dissolved catalyst,

4 for example about 0.01% in the case of aluminum chloride at atemperature of 212 F.

The invention will be lmore clearly understood from the followingdetailed description of a specic example thereof read in conjunctionwith the accompanying drawings which form a part of thisspecicationandirrr which:

Figure 11 is aschematic flow diagram of a process for isomerizing lightparaiini-c hydrocarbons such as pentane, hexane, etc. and

Figurel is a chart illustrating the remarkably increasedl amounts ofaluminum chloride which can be dissolved in light naphtha hydrocarbonssuch; asipentanes and" hexanes when the solution i temperature isapproached from the high temperature-side rather than from the lowtemperature side.

Referring to Figure l, the charging stock for thefisomerization processmay be a hexane cut of a virgin light naphtha. Alternatively, the chargemay beA normal pentane, normal. hexane, methyl pentaneeV etc. from anysourcev whatsoever' but. said .stocks should not contain more than about2 lar-3% of; aromatics and4 they should befsubstan.- tially,l free fromolefins. About 1/2 to /aofthe. chargeintroduced from source I0 maybepassed by line I Ifto absorbertower. I2 for absorbing hydrogenchloride introduced in recycle; gases from linel I 3 and make-uphydrogen chloride introduced from source I4, any unabsorbed gases beingventedY through 1ine:I5. The hydrogenchloride solution leavesthe baseof. absorberA through line I5 and is introduced by pump Il through`heater H3V to a low point .in reactor tower I9.. The amount of hydrogenchloride. thus introduced. shouldibe, about'. 2. to 10%Y for.v exampleabout 5: or. 6% by weightv of: the total hydrocarboncharging: stockintroduced into the reactor;

The remaining one-fourth tot one-half of the. charging stock. may beintroduced by linev 2G through. pump 2l and heater 22 inton solutiontank.23' or 23a. Such tanks maybe of any de sired'size or shape andmay-be: provided with stirring or agitating means (not shown) but it isusuallysuii'icient to employ simple cylindrical towers packed with lumpaluminum chloride introducedi'rom source 24 by lines 25 and 25a. Downowthrough the' solution tanksis advantageousv since the hydrocarbon streamwill serve to iiush any complex formed out of saturator and carry itinto. thereactor proper; By employing two solution tanks, one may be on.stream under pressure While the other is beingA charged with solidaluminumchl'oride. These solution tanks mayv be steam jacketed orprovided. with other conventional heating means in order to insure thenecessary high temperatureemployed for effecting solution or.alternatively they may simply be WelLinsulated and the heat may besupplied by preheatingv that portion of the charging stock that ispassedtherethrough; Theresulting-solu-l tions are passedfromthersolution tanks through lineZB-andcooler 2'1V and line-28'toreactor I9.Y Instead of employing acooler' 21 Imay employ the reactoritself as a` cooler thereby` minimizing theI load ong heat exchanger. I8andinthis case Imay by-pass co.oler.21 bymeansofline 29. In order itoprevent complex formation in the solution tanks I may pass at least apart of thehydrogen from, source 30 through line 3l.- to that portionofthe charge entering the solution tanks, the remainder of 'the hydrogenbeing introduced through linei32. directlytov a low point of reactortoweipll,

The solution tanks may be operated at a temperature which is higher thanthe temperature in reactor I9 and said tanks may operate within theapproximate temperature range of about 150 to 300 F. or higher. Forexample, when the reactor is operated at about 212 F. the solution tanksmay be operated at about 250 F. It is not always necessary, however, forthe solution tanks to be at higher temperatures than the reactor sincemany features of the invention are applicable with solution temperaturesas low as 200 F. or even 150 F. The pressure maintained in the solutiontanks should be at least suflcient vto maintain the hydro-carbons inliquid phase and in this particular example a full reaction pressure ofapproximately 850 pounds per square inch is maintained.

It is essential not only that the temperature and amount of solventcharged to the solution tanks be carefully controlled but also that thetime and extent of contact in the solution tanks be adequate forincorporating the desired amount of catalyst in the hydrocarbonsolution. Generally speaking, the space velocity through the solutiontank should be not more than about 1 volume of liquid hydrocarbon perhour per volume of solid aluminum chloride in the tank and the aluminumchloride should be of suiciently small particle size to present a largesurface area, 10 mesh to 1A inch particles being satisfactory in largecommercial installations. If higher space velocities are employed or ifthe free sur face area of aluminum chloride is diminished because ofunduly large particle size or the formation of complex, then the amountof aluminum chloide dissolved may decrease to about 1/2 or even to aslow as 1/5 the amount indicated by the solubility charts in Figure 2.The use of hydrogen and the pretreatment of hydrocarbons entering thesolution tanks are therefore important in insuring the rapid so-lutionrate and in enabling the operation of the solution tank at the lowestpossible temperature. A reasonable excess of solid aluminum chlorideshould always be maintained in the solution tanks. This can bevaccomplished by lling one solution tank with solid aluminum chloridewhile another solution tank is on stream.

The total amount of dissolved aluminum chloride which is introduced intothe reactor in this example is about .5 pound per barrel of total stockcharged. The amounts required will vary with particular charging stocksand may be less for example in the case of normal pentane than in thecase of a hexane or methyl hexane. amount in any particular case canreadily be determined either by determining the heat of hydrolysis ofthe complex in reactor or by analyzing such complex to determine itshydrocarbon content. The make-up aluminum chloride should be added atsuch a rate as to maintain the heat of hydrolysis of the catalyst in thegeneral vicinity of about 300 to 380 calories per gram but notsubstantially in excess of about 380 calories per gram. On a compositionbasis the hydrocarbon content of the catalyst should be maintainedwithin the approximate range of about 23 to 40% but it should not besubstantially less than about 23%. The exact limits which may beapproached will vary somewhat from the values above depend ing uponreactor temperature. The limits given were determined at 212 F. howeverit will be found that operation at temperatures up to 300 F. will notrequire greatly diierent operating limits. The precise temperature atwhich the solu- The tion tank should be operated can readily bedetermined from the data plotted in Figure 2.

Referring more specifically to Figure 2, it will be noted that if thesolution tanks are maintained at 200 F. less thanA 1% by weight ofaluminum chloride can be dissolved in the hydrocarbon regardless of thelength of time allowed for obtaining said solution (point X on curveAB). However, if the incoming solution is heated to about 230 F. (pointY on curve AB) and given a sufliciently long period of contact with anexcess of aluminum chloride at said temperature and then cooled to 200F. (point Z on curve CD) about 2.5% by weight of aluminum chloride may-be dissolved in the hydrocarbon. The remarkable fact is that' thislarge amount of dissolved alumnum chloride apparently stays in solutioneven after prolonged contact with an excess of undissolved aluminumchloride. By effecting the solution at a higher than desired solutiontemperature and then cooling back to desired solution temperature I thusincorporate more than twice as much aluminum chloride into the solutionas could otherwise be incorporated. Curve AB represents the maximumamount of aluminum chloride that can be dissolved in such hydrocarbonsas pentanes, hexanes and light naphthawhen the solution temperature isapproached from the low temperature side. Curve CD represents theamounts of aluminum chloride that can be dissolved when the solutiontemperature is approached from the high temperature side, i. e., atemperature at least 25 to 30 degrees higher than the desired solutiontemperature. Byheating to a higher-than-desired solution temperature andthen coo-ling back tordesired solution temperature I may incorporate anadequate amount of catalyst material into the hydrocarbons to take careof the entire make-up requirements of the system and I thus solve thevexatious problem of make-up catalyst introduction which has heretoforeconfronted the art.

The reactor in this case is a simple cylindrical vessel about feetinheight and of such diameter that whenV about two-third-s orthree-fourths lled with aluminum chloride-hydrocarbon com'- plex thespace velocity will be of the order of about .4 to Ll, for example about1, volume o-f liquid charging stock per hour per volume of complex inthereactor. It is preferably operated at a temperature within the rangeof to 300 F.. e. g., about 212 F. and under a pressure of the order of5.00 4to 1500 pounds per square inch, e. g., about 850 pounds per squareinch. Hydrogen is introduced from source 30 at the rate of about 50tor300 cubic feet per barrel of stock charged, e. g., about 180 cubicfeet per barrel. The aluminum chloride solution is preferiablyintroduced into the reactor at a separate point from that at which thehydrogen chloride solution is introduced and a considerable portion ofthe hydrogen is preferably introduced at a low point in the reactor inorder -to strip out hydrogen chloride and hydrocarbons from spentcomplex which is removed either continuously or periodically shouldbelunderstood thata tubular reactor may be employed or a stirred reactoror a reactor or any other known type.V

Reaction products separate from the catalyst complex in the upper ,partof reactor I9 and are taken overhead through line 34 to the hot settler35. The entrained catalyst complex settles out and is returned to thereactor through lines 35, V31. The product stream then passes throughpressure reducing valve 38, cooler 39 and line 4B to cool settler 4lwherein additional catalyst material may settle out and be returned bypump 42 and line 3l' to reactor i9. Gases may leave the tcp of coolsettler 4l through line 43 to line I3 which leads to the base ofabsorber tower l2. The liquid product stream flows over weir 44 and iswithdrawn through line i5 4to hydrogen chloride stripper 46 which isprovided With a suitable heating means lll at its base. Hydrogenchloride and .lighter gases are stripped .out of the product in stripper46 and returned by lines 48 and I3 to absorber tower I2.

The stripped bottoms pass through cooler 49 to neutralizing system '5,0wherein they are scrubbed with caustic introduced through source l. Thecaustic treated Vproductmay then pass to a washing system 52 whereinneutralization products :are scrubbed out by water introduced fromsource 53. The water washed product may then pass through 1ine'54 tofractionator A which in this case may be'depentanizer 55, the pentanesand lighter hydrocarbons being taken overhead through line 56. Thebottoms from tower 55 pass through line 51 to fractionator B which inthis case is neohexane tower 58, the neohexane product being removed.frornthe top of this tower through line 59. The bottoms from tower 58pass through line 6B lto fractionator- C which in this vcase is a column5l which separates methyl pentanes and normal hexane from heaviernaphthenic hydrocarbons. The methyl pentanes and normal hexane are takenoverhead through line Sp2, condensed in cooler 63 and recycled to theconversion system through line B4. The heavier naphthenic hydrocarbonsare withdrawn through l line 65 and may serve vas charging stock for adehydroaromatization system or be used 'as solvents ormotor or aviationfuel components.

The fractionation system hereinabove described is schematic andillustrative only and it should l be understood that each column ortower is provided with suitable reflux means at its top and reboilermeans at its base. If desired, additional columns may be employed fordebutanizing the product, separating normal pentane fromisopentane, etc.The fractionation system per se forms no part of the present inventionand any desired type of fractionation system Inav be used. Thefractionation system may simultaneously fractionate a part or allV ofthe charging stock, i. e.. charging stock may be introduced from source55 and line 5'! to column 55 instead of or in addition to the chargeintroduced from source lil.

In the specic example hereinabove described the charging stockwas ahexane out of paraflinic virgin light naphtha, and the desiredproductwas neoheXa-ne although the product stream likewise usuallycontains smaller amounts of cyclopentane and other hydrocarbons. Theinvention is equally applicable to a pentane-hexane charging stock inwhich case the isopentane and neohexane streams may be separatelyrecovered by suitable fractionation or the product stream may containpentanes (chiefly isopentane) as well as neo hexane. Whenheptanes are`isomerized in such -a system temperatures may be slightly lower,vhydrogen pressures somewhat higher and therecycled stream shouldconsist essentially of `methyl hexanes, normal heptanes and naphthenesbeing withdrawn from the system through line 65.

When the process is employed for converting normal pentane toisopentane, the hydrogen requirement maybe substantially reduced and` infact it may be practically eliminatedparticularly when the proper amountof a cracking inhibitor is admixed with the charging stock or separatelyintroduced into the reactor. An amount of aromatic within theapproximate range of .02 to 2 or 3%., for example about .5%,is a veryeffective cracking inhibitor best results being obtained by a'dmxingabout .5% of benzol `with the charging stock before it is introducedinto the reactor. Naphthenes may likewise serve as cracking inhibitorswhen employed in amounts within the approximate range of l to 20%, forexample about 5 to 10%. Avoiding the necessity of using hydrogen inthe,reactor makespossible the operation of .said reactor at lower pressuresbut the pressure Vshould be sufcient to maintain substantially liquidphase conversion conditions. Even when'no hydrogen is employed in thereactor it is desirable, though not absolutely essential, to maintain ahydrogen pressure in solution tanks 23 and 23a. ln order to-prevent orminimize complex formation therein. For this purpose hydrogen pressuresmay be of the order of 50 to 500 pounds per square inch, for example,about 200 pounds per square inch, and since little or no hydrogen isactually consumed in the solution tank, it is only necessary to add theamount of hydrogen which is continuously dissolved in the hydrocarbonsleaving the solution tank. For such operations with down flowsaturators, a hydrogen atmosphere may be maintained in the upper part ofthe solution tank above the liquid interface in such manner as tocontact the hydrocarbon ybefore it reaches the aluminum chloride. Thedissolved hydrogen .in `the hydrocarbon will then prevent complexformation.

For butane isomerization and likewise for pentane isomerization when .5%of benzol or equivalent amount of other cracking inhibitor is employed,the conversion system may beconsiderably simplied. Absorber tower l2 maybe eliminated and instead of employing hot and cold settlers a singlesettler may be employed and operated at a pressure of the order of about200 pounds per square inch and at a temperature of about atmospheric toF. Under these conditions most of the hydrogen chloride is dissolved inthe .liquid product and any minor amounts of lighter gases may be venteddirectly from the settler without appreciable hydrogen chloride losses.Hydrogen chloride in this case may be recycled directly from the top ofthe stripper to the charging stool: entering the base of thereactor. Theelimination of the necessity of using an absorber makes `available agreater portion of the charging stock to serve as a solvent formakeupaluminumrchloride so that in this case solution tanks 23 and 23amay operate within the lower portion of their operating temperaturerange and the tendency toward complex formation in these solution tanksis thereby materially reduced. When charging pentanes or butane, the useof hydrogen allows the toleration or" substantial amounts `of hydrogenchloride in the feed to the saturator Without excessive complexformation.

Where the amount of recycled hydrocarbon per" mits, itis desirable thatsuch recycled hydrocar-` bon be introduced into the solution tanksinstead of fresh charge. The recycled hydrocarbon has already beencontacted with catalyst and is thus free from undesirablecomplex-forming materials which may be present in untreated fiashcharging stock. Thus all of the fresh charging stock in the examplehereinabove described may be introduced through line Ii to absorber l2and the recycled hydrocarbons from line 6d may serve as the sole sourceof hydrocarbons for passage through solution tanks 23 and 23a.

In any isomerization system it is important to prevent dissolvedaluminum .chloride from being taken overhead with a product steam and tothe settlers, stripper, etc. Such dissolved aluminum chloride`carry-over not only results in expensive catalyst losses but it alsoresults in various corrosion and line-plugging problems, particularly inthat part of the system which includes the settler and the stripper andlines communicating therewith. In order to prevent such carry-over Iregulate the introduction of dissolved aluminum chloride into thereactor so as to maintain a heat of hydrolysis of aluminum chloridehydrocarbon complex in the reactor Within the approximate range of 300to 380 calories per gram. In other words, I maintain the catalyst at ahighly active level by preventing its hydrocarbon content from exceedingabout 40% but I maintain its hydrocarbon content at at least about 23%in order that it may remove substantially all of the aluminum chloridefrom the introduced solution so that a negligible amount of aluminumchloride, i. e., an amount of the order of about .01% is carried over insolution in the eiiiuent product stream. The remarkable tendency of analuminum chloride complex to combine with aluminum chloride and thustake it out of solution makes it important to prevent the formation andaccumulation of any appreciable amounts of complex in solution tanksthemselves; hence the importance of preventing the formation orintroduction of hydrogen chloride in solution tanks, when charginghexanes or higher, and maintaining the solution tanks under hydrogen.pressure in order to prevent complex formation.

While I have described a specic example of my invention and specificoperating conditions in connection therewith, it should be understoodthat the invention is not limited to this example nor to the describedconditions since numerous other modifications and alternative operatinglconditions will be apparent to those skilled in the art from the abovedetailed description.

I claim:

1. In a method of adding make-up active metal halide to a continuousconversion system employing a Friedel-Crafts catalyst the improvementwhich comprises dissolving said active metal halide in a light normallyliquid paranic hy- 10 drocarbon at high temperature within the range ofabout 150 to 300 F. and under a hydrogen pressure for inhibiting complexformation and then cooling the resulting solution to a lower temperaturewhich is atleast about 25 lower than said high temperature in order toobtain in said solution a substantially larger amount of dissolvedactive metal halide than could be incorporated therein if the solutionhad been effected at said lower temperature.

2. The method of claim 1 wherein the high temperature is at least about200 F.

3. The method of operating an active metal halide hydrocarbonisomerization system employing an active metal halide hydrocarboncomplex which method comprises maintaining the hydrocarbon content ofsaid active metal halide-hydrocarbon complex within the approximaterange of 23 to 40% by weight by adding thereto a solution of activemetal halide in a light normally liquid parafiinc hydrocarbon whichsolution is formed at an elevated temperature and pressure in thesubstantial absence of deleterious complex-forming materials and undersubstantial hydrogen pressure.

4. The method of claim 3 wherein the solution is formed under a hydrogenpressure within the approximate range of 50 to 500 pounds per squareinch.

5. The method 0f incorporating a larger amount of aluminum chloride in alight normally liquid paraflinic hydrocarbon at a particular temperaturewithin the approximate range of 150 to 250 F. than could be introducedinto said hydrocarbon by prolonged contact and intimate mixing of saidhydrocarbon with the aluminum chloride at said particular temperaturewhich method comprises, contacting said hydrocarbon in the absence ofcomplex-forming materials and under a substantial hydrogen pressure witha large excess 0f aluminum chloride at a temperature at least 25 F.higher than said particular temperature and for a period of timesufficient to effect substantial saturation and subsequently coolingsaid solution to said particular temperature.

RICHARD C. WAUGH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Iverson Dec. 11, 1945 Certificate of CorrectionPatent No. 2,425,074. August 5, 1947. RICHARD C. WAUGH It is herebycertified that errors appear in the printed specification of the abovenumbered patent requiring correction as follows: Column 3, line 69, forprecess read process; column 5, line 36, for chloide read chloride;column 6, line 17, for alumnum read alumtnnm; column 9, line 14, forsteam read stream; column 10,

line 21, claim 3, for paraiinc read parajm'c; and that the said LettersPatent should be read with these corrections therein that the same mayconform to the record of the case in the Patent Olice. i

Signed and sealed this 16th day of September, A. D. 1947.

[SEAL] THOMAS F. MURPHY,

Assistant Commissioner of Patents.

